Suspension system for trailers



Nov. 19, 1968 G. M. BELLAIRS SUSPENSION SYSTEM FOR TRAILERS Filed Sept.26, 1966 INVENTOR George M. Bel/airs United States Patent 3,411,806SUSPENSION SYSTEM FOR TRAILERS George M. Bellairs, 719 S. Oakland St.,Webb City, Mo. 64870 Continuation-impart of application Ser. No.394,918, Sept. 8, 1964. This application Sept. 26, 1966, Ser. No.581,801

2 Claims. (Cl. 280-124) ABSTRACT OF THE DISCLOSURE A suspension unit forvehicles including a frame for attachment to the vehicle, a hollow mountslidably carried within the frame and a stub axle traversing the mount,secured thereto and having at least one wheel carried by an end thereofextending outwardly from the mount. Load cushioning spring means areinterposed between the mount and the top of the frame and stabilizingspring means are interposed between the mount and the bottom of theframe, vertical reciprocation of the mount, against said spring means,being permitted by a plurality of up rights which are embraced bycorresponding sleeves carried by the mount.

vided iwth tandem spring arrangements employing leaf springs whichdepend from hangers and support a correspondnig axle of the trailer.These arrangements are inherently weak since the spring itself must bearthe braking and turning load of the suspension structure as well as formthe shock absorbing system therefor. An acute problem resulting fromthis arrangement is that upon braking of a moving truck and trailer, themomentum of the trailer and the braking action on the wheel act inopposition and therefore tend to twist the axle and place high stresseson the springs, particularly at their hanger connections. This oftencauses breakage of the spring or hanger, and even if breakage does notoccur, the wheel will not be properly aligned with the truck because ofthe twisting force on the axle whereby the tire is caused to jump andskid along the road surface creating so-called wheel or axle hop.

Many attempts have been made to alleviate wheel hop, incluuding theutilization of torque arms, specially built hangers, and sundryequalizer designs. However, none of these has suitably solved theproblem and generally have just added to the expense of the suspensionsystem. Further, spring designs developed for various smaller vehiclesare unsatisfactory for the loads carried by freight trailers.

Accordingly, it is the primary object of my invention to replace theexisting conventional tandem-type suspension arrangements normally usedin large trailers with a suspension system utilizing independentsuspension units, each of which units icludes a novel oombiation of axlemounting structure and spring means for eliminating wheel hop while alsoproviding smooth shock-absorbing action.

An important object of this invention is to provide a suspension unitdesigned to include axle mounting structure and spring means whichoperate substantially independently for the respective functions of axlealignment and shock absorbing, whereby the spring means will not besubjected to the abnormal stresses created by braking action insuspension systems heretofore utilized.

Yet another object of the instant invention is to provide a suspensionunit of the aforementioned character wherein the axle mounting structureis sepecially designed to provide an equalized distribution of thebraking stress and thereby preclude the presence of weak points in thesuspension system, to the end that the danger of an accident isminimized and maintenance costs are substantially lowered.

Other objects include details of construction which will become apparentfrom the following specification and accompanying drawing wherein:

FIGURE 1 is a fragmentary, side-elevational view showing my suspensionunit, with the wheels attached thereto shown in dashed lines;

FIG. 2 is a rear view thereof;

FIG. 3 is an enlarged, cross-secional view taken along line 3-3 of FIG.2;

FIG. 4 is an enlarged, cross-sectional view taken along line 4--4 ofFIG. 1; and

FIG. 5 is an enlarged, cross-sectional view taken along line 55 of FIG.1.

The individual suspension unit of the present invention, broadlydesignated by the reference numeral 10, is adapted for attachment to avehicle 12, and most particularly adapted for use with heavy dutyfreight trailers. Unit broadly comprises a frame 14 which receives amount 16 for relative vertical sliding movement. Mount 16 has ahorizontal stub axle 18 traversing the same and rigidly secured theretoand is maintained in a normal vertical position by load cushioningspring means 20 disposed above axle 18 and stabilizing spring means 22disposed below the axle.

Frame. 14 includes a top plate 24 adapted to be secured to vehicle 12 bya pair of brackets 26. A plurality of uprights depend from plate 24,and, in the illustrated embodiment, comprise six relatively spaced bolts28 which are each threaded at both ends. Bolts 28 are disposed in twoaligned sets extending parallel to the axis of axle 18, one of the setsbeing disposed forwardly of axle 18 and the other set rearwardly therof.Bolts 28- extend through suitable corresponding openings in plate 24 andbrackets 26 to receive opposed nuts 30 for rigidly securing plate 24 independing relationship to vehicle 12.

Mount 16 is hollow and is defined by side panels 32 and end panels 33arranged in a transversely rectangular configuration and presenting anupper open end 34 and lower open end 36. A horizontal partition 38 iswelded to side panels 32 within mount 16 below end 34, and a crossmember 40 is secured between partition 38 and end 36 and extendslongitudinally of axle 18. Axle 18 extends through side panels 32 ofmount 16 and is rigidly secured to partition 38 and cross member 40therebetween.

A plurality of elongated upstanding sleeves 42 extend through partition38 and are welded or otherwise suitably secured to end panels 33, therebeing a sleeve 42 aligned 'with each bolt 28 for surrounding engagementtherewith. Mount 16 is thereby slidably carried by bolts 28 for movementrelative thereto toward and away from top plate 24 and a bottom plate 44which is secured to the lower threaded ends of bolts 28 by correspondingopposed nuts 46. Axle 18 is thus disposed in intersecting relationshipto the axis of movement of mount 16.

A box-like structure 48 is disposed about frame 14 and comprises anglebraces 50 at the vertical edges thereof and a plurality of horizontalbars 52 interconnecting the adjacent inner faces of angle braces 50 atthe upper and lower ends thereof. A pair of bolts 54 extend through anopposed pair of lower bars 52, are journalled through correspondingsleeves 56 depending from bottom plate 44 and coupled to nuts 55 tothereby secure structure 48 to frame 14. Structure 48 could also besecured to frame 14 by welding the same to top plate 24.

Load cushioning spring means 20 is interposed between partition 33 andtop plate 24, and, in the illustrated embodiment, comprises four coilsprings 58 disposed in a pattern surrounding the vertical axis ofmovement of mount 16. Springs 58 may be maintained in proper position bycollars 60 which extend inwardly from top plate 24 and partition 38 foreach spring. Stabilizing spring means 22 includes a pair of coil springs62 interposed between cross member 40 and bottom plate 44. Springs 62are preferably aligned so that their respective lines of action lie inthe vertical plane defined by the axis of axle 18 and the axis ofmovement of mount 15. Collars 64 on cross member 44 and bottom plate 44serve to maintain springs 62 in operating position. The opposed ends ofsprings 58 and 62 engage mount 16 and the corresponding plates, and havea strength proportion to maintain mount 16 in a desired verticalposition between plates 24 and 44.

In use, unit 19 is rigidly attached in depending relationship to vehicle12 by nuts 3-0 which connect brackets 26 and top plate 24. A pair ofdiagonal braces 66 may be added to interconnect the lower end of unit 10to vehicle 12 to further support the unit. Referring to FIG. 2, a wheelassembly 68 is rotatably attached to the spindle 70 of stub axle 18,there being suitable braking means operably coupled to brake flange 72for stopping wheel assembly 68. A unit 10 is provided for each set ofwheels 68 on the trailer whereby the latter is supported by therespective load cushioning spring means 20.

When wheels 68 encounter bumps or depressions in the road surface beingtraveled over by vehicle 12, the wheels will follow the obstacle andcarry mount 16 therewith, the latter vertically sliding relative tobolts 28 against the action of coil springs 58 for shock-absorbingthereby, which absorbing action is stabilized by coil springs 62. Thecooperation between sleeves 42 and bolt 28 provides a smooth slidingaction for the reason that the springs 58 and 62 are optimumlypositioned with respect to the axis of movement of mount 16 and the axisof axle 18 to effect an equalized spring action and thereby preventbinding of mount 16 on bolts 28.

When wheels 68 are braked through flange 72, the momentum of vehicle 12tends to continue the rectilinear movement of axle 18, while thestopping action of wheels 68 tends to hold the outer end of axle 18 infixed relationship with the road surface. This tends to twist axle 18but is combatted by the cooperating surfaces of sleeves 42 and bolts 28which hold mount 16 and thereby axle 18 in fixed relationship withrespect to vehicle 12, to the end that wheels 68 are maintained inparallel relationship with the movement of vehicle 12 and wheel hop isthereby prevented. The opposed momentum and braking forces are absorbedby mount 16 which evenly distributes the stresses thereon to bolts 28.The particular axle mounting arrangement thus is very important inguarding against breakage at some point in suspension unit 10. Inaddition to the axle twist protection afforded by frame 14, the later ismounted in depending relationship to vehicle 12 so that the load isplaced directly over the load cushioning springs 58 rather than, forexample, having the springs disposed laterally of the trailer andthereby creating a weak point in the suspension system between thesprings and the attachment structure to the vehicle. Since the axletwist forces are absorbed by mount 16 and its associated frame 14,springs 58 and 62 are not stressed in any manner by the braking action,and thus will not be prone to breaking as has been the case with springsheretofore used. The shock absorbing action of the springs may bemomentarily stopped when braking of the vehicle leads to binding ofmount 16 on bolts 28 to prevent wheel hop, but the shock-absorbingoperation is not particularly important during the short time involved.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. A suspension unit for vehicles comprising:

a frame having a top, a bottom and a plurality of uprightsinterconnecting the top and the bottom,

said top being adapted for rigid attachment to the frame of the vehiclein depending relationship thereto;

a mount slidably carried by each of said uprights for vertical movementrelative thereto toward and away from said top and said bottom;

a horizontal wheel axle traversing the mount and rigid ly securedthereto between said top and bottom in intersecting relationship to theaxis of said movement of the mount;

load cushioning spring means interposed between the mount and said top,said means including a plurality of springs disposed in a patternsurrounding said axis; and

stabilizing spring means interposed between the mount and said bottom,said means including a pair of springs disposed to lie in a verticalplane defined by said axis vof movement and the axis of said axle,

said mount being hollow and provided with a horizontal cross memberextending longitudinally of the axle and rigidly secured to the latterbetween the stabilizing spring means and the axle, said mount beingprovided with a horizontal partition interposed between the loadcarrying spring means and the axle and rigidly secured to the latter,

there being a plurality of said uprights in spaced apart relationshipand disposed forwardly of said axle, and a plurality of said uprights inspaced apart relationship and disposed rearwardly of said axle, saidmount having an elongated upstanding sleeve in surrounding engagementwith each upright respectively.

2. The invention of claim 1, said axle being a stub axle and having atleast one wheel carried by an end thereof extending outwardly from saidmount.

References Cited UNITED STATES PATENTS 1,314,982 9/1919 Reed 267-601,054,590 2/1913 Mesure 26760 1,931,708 10/1933 Ross 267--60 PHILIPGOODMAN, Primary Examiner.

